Method of making rimming steel



Patented Sept. 3, 1929.

UNITED. STATES PATENT OFFICE.

DAVID WILLIAMS, F MASSILLON, AND MARCUS A. GROSSMANN, OF CANTON, OHIO, ASSIGNORS TO MIDWEST METALLURGICAL CORPORATION, OF NEW YORK, N. Y.,

METHOD 01E MAKING RIMMING STEEL.

No Drawing,

Heretofore in the manufacture of rimming or basic open hearth steel of the eifervescing type, that is a'steel which boils violently 1n the mold after pouring on account of the con- 5 tinned evolution of gas at solidification, it

has been found that the practice is materially improved by the addition to the molds of small quantities of some fluorin compound as for instance, calcium fluoride or fluorspar. The addition of a fluoride under these conditions causes a very marked improvement in the quality of the ingot, the skin being thicker and denser and freer from horizontal blow holes or passages leading inwardly through the skin and the ingot itself more nearly approaches the desired condition in which the molten metal neither falls or rises considerably in the mold,

The present invention is an improvement on the fluoride process heretofore described and consists, in the preferred method of practicing it, in adding small quantities of metallic aluminum to the metal in the ladle before it is poured into the molds and in adding a fluoride in the molds, either with or without small additional quantities of aluminum, to control still further the action of the metal in the mold. While as stated, it is preferable to add the aluminum in the ladle, as by so doing more perfect results may be obtained, it may also be possible to produce satisfactory results by making use of a molten steel which already contains the requisite amountv of aluminum. Further, while aluminum is the preferred agent for controlling the effervescence, the invention in its broadest aspect is not limited to the use of this particular substance as silicon and other equivalents may also be used wholly or in part.

While the action of these agents cannot be stated definitely it seems probable that the of fect of the aluminum or its equivalent is to increase the solubility of the metal for gases and therefore decrease the effervescence; and that the fluorin produced by the reaction of the fluoride tends to combine in part at least with the aluminum or silicon residue, and remove it from the scene of reaction either in the form of a volatile gas or by precipitating an insoluble substance thus increasing the liquidity of the metal down to the temperature of the change of state so that the gases go off more readily. Of course, it will be understood that the foregoing is applicants present Application filed J'anuary 30, 1928. Serial No. 250,741.

understanding of what takes place and that this may or may not be correct, the same be 111g here stated for the purpose of informing the public fully as to the invention. It has, however, been completely demonstrated by the production of considerable quantities of steel in accordance With the hereindescribed process that the addition of aluminum or its equivalents and of fluorin or possibly equivalent compounds in the quantities and manner described produces extremely beneficial results in the practice.

In practicing the invention with a steel havmg a range of carbon from 0.06 to 0.08% and manganese 0.28 to 0.35%, we have found that the addition of from 2 to 6 ounces of metallic aluminum per ton of steel in the ladle and of from A of an ounce to 8 ounces of fluorspar per ton of steel in the mold produces excellent results. It will be understood that 1n practicing the invention the melter will vary the amount of aluminum in accordance with the condition and composition of the steel, it being Well understood that the effervescence will be greater where the casting temperature is higher and. consequently somewhat more aluminum may be required. Also, that with higher carbon and higher manganese the amount of aluminum required will be less. In practice it is convenient to add small quantities of shot aluminum in the molds after 3 or 4 inches of steel has been poured, the amount being based on the melters judgment. This amount is not over six ounces per ton.

While it is fully recognized that the use of fluorspar as heretofore proposed in the manufacture of steel is highly beneficial and has produced astonishing results, it is found that in the commercial practice of the fluoride process the use of aluminum as described herein assists materially in controlling the aciion and in accomplishing the desired resu ts.

We recognize that aluminum alone has been used for many years in effervescing steels. We have also pointed out above that recent improvements in the art involve the use of fluorides. What we claim as our invention is the controlled use of aluminum with fluoride. This is for the reason that too little aluminum or too much fluoride causes the steel to drop too much in the mold in solidifying, giving an unsatisfactory ingot, whereas too much aluminum or too little fluoride causes the steel in the mold to rise, which is also an unsatisfactory condition. We have shown that the presence addition or cfiect of too much fluoride can be corrected by the use of aluminum, and the presence, addition or eflect of too much aluminum is in the same Way controlled by fluoride.

What we claim is: a

1. The method of controlling the quali of rimming steel which comprises control ing the action of the metal during solidification in the ingot mold by the additionto the metal after tapping of an agent which lessens the efi'ervescence and adding to the metal in the ingot mold a substance capable of uniting with said a ent.

2. T e method of controlling the qualit of i rimming steel which comprises control ing the action of the metal during solidification 20 in the ingot mold by the presence therein of the equivalent of from two to six ounces of aluminum per ton of steel, a portion of which is added in the ingot mold together with from one-half to eight ounces of a fluoride per ton 25 of steel.

In testimony whereof we aflix our signatures.

DAVID WILLIAMS. MARCUS A. GROSSMANN. 

